Coal feed tube



1954 w. s. ANDERSON 2,665,796

COAL FEED TUBE Filed Nov. 19, 1949 tos and many other substance of a similar nature, and an inner layer 2| which has principally good wearing and friction-reducing characteristics, for example sheet metal. Since the wear is not great, the metal sheet may be quite thin, a 28 gauge galvanized sheet metal having been found to give Very satisfactory results in service. The outer tube I2 may be and preferably is thicker and stronger, a 16 or 11 gauge galvanized steel sheet metal having been found to provide the necessary strength'and rigidity to do the required work. When a metal liner is used it is permissible to use a thinner outside tubular member than would otherwise be suitable. A single thickness of asbestos paper has been found to give good sound-deadening effects when used as the intermediate space filler.

For convenience in manufacture, it is preferable to place the layer of metal 2| and the layer of sound-deadening material 20 around thehelicoid l8 and to insert this sub-assembly in the main coal tube I2. The helicoid may be attached at its ends to the coal tube or it may be retained by friction. It is stiff enough to hold its shape between its ends. However, it has some resilience and may be twisted to reduce it diameter before the lining layers 2|, 20 are placed thereon so the sub-assembly may be readily inserted in the coal tube 12. Re-expansion of the helicoid causes the sub-assembly to be firmly retained in position within the coal tube.

It will be seen that the inner surface is almost or completely sound-insulated from the outer tube and that the outer solid tube forms a sound barrier so that, consequently, there can be no noticeable passage of sound to the outside, either through the sides of the coal tube to the adjacent air or through its ends to the furnace installation or to the air. Such sounds as may tend to travel through the tube are muffled by the closed arrangement at the ends. The form illustrated has the heavier solid tube on the outside. It may be on the inside it suitably strong and rigid bearing and drive assemblies are provided for the tube assembly as a whole. The solid tubes are shown to be of considerably different thickness and this is believed to be beneficial because they then have different natural periods of vibration and the outer tube more completely dampens the vibrations and overtones caused by particles falling on the inner tube, but tubesapproaching or reaching unity of ,thickness produce greatly improved quietness over installations which do not have the sound-deadening elements.

While one embodiment has been illustrated and described, it will be understood that there may be various embodiments within the general scope of the invention.

Iclaim:

1. A feed tube for feeding upward on an incline particles of hard material, such as coal and the like, comprising in combination, an outer metal tube mounted on an incline for rotation, a smooth inner metal tube mounted within and spaced from the outer metal tube, and an integrally continuous spirally wound helicoid sheet metal fin mounted within said inner tube and secured at its ends to the tube assembly to rotate therewith, the fin fitting tightly within said inner tube and being open along its inner longitudinal axis, the inner metal tube being thinner and having a different vibration frequency from the outer metal tube whereby sound vibrations imparted to the thin inner tube by particles striking thereagainst are damped or blanked by the thick outer metal member.

2. A feed tube as set forth in claim 1 which further includes a tubular layer of sound-damping sheet material between the inner and outer metal tubes.

3. A feed tube for feeding upward on an incline particles of hard material, such as coal and the like, comprising in combination, an outer relatively thick-walled metal tube rotatably mounted at an incline in bearing supports, an inner smooth relatively thin-walled metal liner tube mounted therein and spaced therefrom, a relatively thin layer of insulating material between said metal tubes, and an integrally continuous spirally wound helicoidal sheet metal screw feed fin secured only at its ends within said liner tube and tightly held therein along its length by the resilience of reexpansion, the feed fin having such radial width as to leave a central axial opening therein such that particles can fall back over the fins and strike the surface of the inner tube, said inner and outer tubes having thicknesses and periods of vibration sufiiciently different to minimize the transmission of sounds past the outer tube to the surrounding medium, the lower end of the feed tube assembly being positioned in a coal bin and the upper end being positioned in an enclosed delivery header of a furnace.

WILLIAM S. ANDERSON.

References Cited in the file of this patent UNITED STATES PATENTS Rogers Oct. 14, 1947 

